The principal objective of this study consists in establishing the relationship between nutrition and the physical, mental and social development of children. For this purpose 2 groups of 17 children each, are being studied comparatively; one left in the typical conditions of their poor and malnourished environment and the other which from the fourty-fifth day of gestation has been given food supplementation. The project therefore is in the form of an intervening longitudinal epidemiological study introducing one variable. It has been observed that the supplemented group is significantly different in various aspects, among them: 1) The time between two consecutive gestations has been reduced in 30 per cent, 2) The children are 8 per cent heavier at birth and with different body proportions (the lower segment longer). 3) The physical activity of the children is anything up to 5 times greater at 18 months of age. 4) Their mental development and personality differ. At present, and in the immediate future, the remaining parameters under study will be analysed statistically. The children at the more predictive ages of from 3 to 5 years will be studied, and new tests will be developed with a view to defining the behavior patterns of the children. It is this latter aspect that will command greater interest.